1. Field of the Invention
The present invention relates to a document display device for displaying electronic documents, and a document display system including a plurality of such document display devices. Examples of the document display device are a device having a display screen to produce displays, and a device using a screen to show displays. The former device is, for example, a stationary or mobile information processing device, a mobile terminal, and an e-book reader. The latter device is, for example, a projector.
2. Description of the Related Art
It is sometimes a case where one person displays and views the same electronic document in different information devices. For example, a user of an information device sometimes transfers an electronic document that is created by using a personal computer (PC) or obtained from a Web site to a mobile information device such as a smartphone or a tablet PC to carry around with him/her. This enables the user to look at the electronic document, which was seen on the personal computer, (or a copy thereof) by using a mobile information device at any place. If such a mobile information device has a document edit function, the user is able to update the electronic document or add a comment thereto at any place. Further, the user is also able to transfer the electronic document that has been updated by using the mobile information device to the personal computer where the electronic document was or to another information device, and then the user is able to view the updated electronic document in the transfer destination information device.
For viewing an electronic document, a user modifies display settings of an information device appropriately. Display settings items are, for example, screen orientation (vertical/horizontal), scaling factor for display, the number of pages to be displayed concurrently, page scroll sequence, display font, split-screen, and color arrangement on screen. In general, software used to display an electronic document, i.e., viewer software, accepts operation for modifying settings while the electronic document is displayed. The user can modify display settings while viewing the electronic document, and thereby the electronic document is easy to see.
There is known a so-called “save workspace” function for storing display settings modified by a user, i.e., the updated display settings. According to this function, when the user performs operation for finishing browsing, display settings at this point in time and the position of the view within the electronic document are stored. When the electronic document is opened later, the preceding display state of the electronic document is reproduced. However, display settings for all the items are not stored in association with the electronic document. Assume that, for example, after looking at a first electronic document, the user views a second electronic document, and modifies display settings for a specific item (settings item common to any document) while viewing the second electronic document. In such a case, when the user views the first electronic document again later, with respect to the specific item, display settings made on the second electronic document are applied to the first electronic document. In short, the display state under which the first electronic document was viewed previously is not reproduced.
In the meantime, as for a display of the same electronic document in different information devices, an information sharing system is proposed by which users of mobile terminals share information added to the electronic document (Japanese Laid-open Patent Publication No. 2008-146245). According to the information sharing system, when a user of a mobile terminal modifies a document page, for example, by adding an underline or a handwritten character thereto, additional information indicating the modification is sent to a management device from which the additional information is delivered to the other mobile terminals. This enables all the users to use the individual mobile terminals to look at an electronic document to which one of the users adds the underline or the handwritten character.
In the case where one person uses a first information device to look at an electronic document, and then, he/she uses a second information device to view the same electronic document as being looked at, it is troublesome for him/her to make display settings in the second information device in a similar manner as made to the first information device for easy viewing. In particular, a person who sees many different kinds of electronic documents, he/she is required to make display settings possibly every time electronic documents to be looked at are changed from one to another. It is labor-intensive and time-consuming. In conventional technologies, even if the first information device is equal to the second information device in model, only a part of display settings items in the first information device is incorporated into the second information device, and the other display settings items are not incorporated thereinto. If the first and second information devices significantly differ from each other in display function depending on the display resolution and the viewer specifications, the display settings applied to one of the devices sometimes cannot be applied to the other just as they are. Even in such a case, however, the small number of display settings items to be modified does not put, to a user, a large amount of work for setting operation.